Process and system for conversion of carbon dioxide to carbon monoxide

ABSTRACT

A process and an apparatus for converting carbon dioxide CO 2  into carbon monoxide CO using hydrocarbons are described. In further embodiments, processes and apparatuses for generating synthesis gas and processes and apparatuses for converting synthesis gas into synthetic functionalised and/or non-functionalised hydrocarbons using CO 2  and hydrocarbons are described. The processes and apparatuses are adapted to convert CO 2  emitted by industrial processes, and thus the amount of carbon dioxide emitted into the atmosphere may be reduced.

RELATED APPLICATIONS

This application corresponds to PCT/EP2012/005309, filed Dec. 20, 2012,which claims the benefit of German Applications Nos 10 2011 122 562.9,filed Dec. 20, 2011; 10 2012 008 933.3, filed May 4, 2012; and 10 2012015 314.7, filed Aug. 2, 2012, the subject matter of which isincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method and a plant for generatingcarbon monoxide from hydrocarbons and CO₂.

Large amounts of carbon dioxide (CO₂), which is regarded as climatedamaging gas, are generated in power generation and other industrialprocesses. Great efforts are made to avoid generation of carbon dioxide.Furthermore, attempts are made to separate the generated carbon dioxidefrom flue gases and to store the carbon dioxide. One example is the CO₂storage or Carbon-Capture-to-Storage concept, abbreviated CCS concept,where the CO₂ is separated from the flue gases, thereafter compressesand stored in appropriate geological formations. The CCS process isexpensive, energy intensive, limited in the storage capacities andis—for various reasons—strongly opposed by the respective population. Atleast in Germany, the technical and political feasibility seems to havefailed.

Another possibility is the use of carbon dioxide as starting materialfor other industrial processes, i.e. as starting material in theplastics industry for producing polyurethane, as it is done by the BayerAG in the project CO2RRECT. Regarding the amounts of involved CO₂, theuse of CO₂ as starting material is only a niche application, since thetotal global production of the end products of such an application istoo low to convert a significant amount of the emitted carbon dioxide.

None of these concepts resulted in applications that are able to bindlarge amounts of carbon dioxide or that are socially acceptable in theirimplementation.

Synthesis gas, or abbreviated syngas, is a gas mixture containing carbonmonoxide and hydrogen that may also contain carbon dioxide. For example,the syngas is generated by gasification of carbon containing fuel to agaseous product having a certain calorific value. The synthesis gas hasapproximately 50% of the energy density of natural gas. The synthesisgas may be burned and thus used as a fuel source. The synthesis gas mayalso be used as an intermediate product in the generation of otherchemical products. For example, the synthesis gas may be generated bygasification of coal or waste. In the generation of synthesis gas,carbon may be reacted with water, or a hydrocarbon may be reacted withoxygen. There are commercially available technologies for processingsynthesis gas in order to generate industrial gases, fertilisers,chemicals and other chemical products. However, most known technologies(e.g. water-shift-reaction) for the generation and conversion ofsynthesis gas have the problem that synthesising the required amount ofhydrogen causes the generation of a larger amount of surplus CO₂ whichis finally emitted into the atmosphere as a climate damaging gas.Another known technology for the production of synthesis gas, thepartial oxidation of methane according to the equation 2CH₄+O₂+2 CO+4H₂,is able to reach a maximum ratio of H₂:CO of 2.0. However, thedisadvantage thereof is the use of pure oxygen that is energyintensively produced.

DD 276 098 A1 describes a more complete material utilisation of naturalgas in steam reforming plants. In particular, a process for generatingsoot from natural gas by means of arc plasma pyrolysis is describedamong others. Further, U.S. Pat. No. 4,040,976 A describes treatment ofa carbonaceous material, especially coal, with carbon dioxide forgenerating a carbon monoxide gas. In said treatment, the carbon dioxideis first mixed with the carbonaceous material and thereafter is rapidlyheated in a reactor together with carbon dioxide at a rate of >500°C./s, and afterwards is rapidly cooled, wherein the heating phase lastsfrom 0.1 to 50 ms and the entire contact time of the reactants islimited to a time range of 10 ms to 5 s. Furthermore, generating carbonmonoxide in a plasma is known from U.S. Pat. No. 4,190,636 A, where aplasma is generated from carbon monoxide, into which solid carbon isintroduced. The resulting products are thermally quenched and filteredso as to obtain carbon monoxide.

EP 0 219 163 A2 discloses a method for generating synthesis gas, whereinhydrocarbonaceous material is decomposed into carbon and hydrogen in afirst reactor chamber, and wherein the carbon is transferred to a secondreactor chamber and reacts with H₂O steam in the second reactor chamber.

GB 873 213 A2 discloses a method for generating synthesis gas, whereinfirst hydrocarbon is decomposed to carbon by means of a catalyst, andthereafter the catalyst in contact with the carbon is exposed to CO₂.

Therefore, a problem to be solved is to provide a method for convertingCO₂, the method being able to efficiently reduce the amount of carbondioxide emitted by industrial processes and to enable production ofchemical products in demand.

SUMMARY OF THE INVENTION

The invention provides a method according to one of claim 1, 11 or 14and an apparatus according to one of claim 18, 24 or 27. Furtherembodiments may be derived from the dependent claims.

In particular, a method for converting carbon dioxide CO₂ into carbonmonoxide CO comprises decomposing a hydrocarbon containing fluid intocarbon and hydrogen by means of introduction of energy that is at leastpartially provided by heat, whereby the carbon and the hydrogen have atemperature of at least 200° C. after the decomposing step.Subsequently, at least a portion of the carbon generated by thedecomposing step is mixed with CO₂ gas, wherein the carbon generated bythe decomposing step cools down by not more than 50% in ° C. withrespect to its temperature after the decomposing step upon mixing withCO₂ gas, and wherein at least a portion of the CO₂ gas and a portion ofthe carbon generated by the decomposing step is converted to CO at atemperature of 800 to 1700° C. This method enables, in a simple andefficient way, converting CO₂ to CO, wherein at least a portion of theenergy required for providing carbon (by decomposing hydrocarbon) isemployed in the converting step in form of heat.

This is particularly true, if the decomposing step takes place at atemperature over 1000° C. and the carbon is mixed with the CO₂ gas at atemperature of at least 800° C., since in this case no additional heator only a small amount of additional heat needs to be provided forconverting CO₂ to CO. Preferably, the heat required to reach thetemperature of 800 to 1700° C. (specifically about 1000° C.) for the CO₂conversion is essentially completely provided by the heat that is usedfor decomposing the hydrocarbon containing fluid. Here, essentiallycompletely means that at least 80%, specifically at least 90% of therequired heat originates from the decomposing step.

In one embodiment, the carbon obtained by the decomposing step and thehydrogen obtained by the decomposing step are both jointly mixed withthe CO₂ gas. Hydrogen does not compromise the conversion and may serveas an additional heat transfer substance. This is particularlyadvantageous, if the carbon and the hydrogen have a temperature of 1000°C. (a preferred conversion or transformation temperature) or above. Inthis case, the gas after conversion is not pure CO but a synthesis gas.Alternatively, the carbon obtained by the decomposing step may beseparated from the hydrogen obtained by the decomposing step prior tomixing with CO₂ gas.

In order to increase the energy efficiency of the method, at least aportion of the heat of at least a portion of the carbon and/or the aportion of hydrogen obtained by the decomposing step may be used to heatthe CO₂ gas prior to the step of mixing the CO₂ gas with the carbonand/or to may be used to heat the process chamber, in which the CO₂ gasis mixed with the carbon. In this sense it should be noted that the COhas a temperature of 800 to 1700° C. after conversion and that at leasta portion of its heat may be used to preheat the CO₂ gas prior to thestep of mixing the CO₂ gas with carbon. It is also possible that atleast part of the heat of at least a portion of the carbon and/or aportion of the hydrogen obtained by the decomposing step and/or aportion of the CO after conversion may be used to generate electricitywhich may be used as energy carrier for introducing energy fordecomposing the hydrocarbon containing fluid.

Preferably, the energy for decomposing the hydrocarbon is primarilyintroduced via a plasma. This is a particularly direct and thusefficient method to introduce energy. Preferably, the decomposing stepis performed in a Kvaerner reactor that enables continuously decomposinga stream of hydrocarbons.

In the method for generating a synthesis gas, at first CO₂ is convertedor transformed into CO as described above and, subsequently, the CO ismixed with hydrogen. Preferably, the hydrogen originates fromdecomposing a hydrocarbon containing fluid into carbon and hydrogen byintroducing energy that is at least partially performed by heat.Therefore, the decomposing step may provide the carbon and also thehydrogen necessary for the CO₂ conversion in one step. In oneembodiment, at least a portion of the hydrogen is generated bydecomposing a hydrocarbon containing fluid at a temperature below 1000°C., specifically below 600° C., by means of a microwave plasma. Whereadditional hydrogen (more than the amount that is obtained by theproduction of the carbon necessary for the CO₂ conversion) is requiredto reach the mixing ratio of a synthesis gas, it is preferred to producesaid hydrogen in an energy efficient manner at low temperatures from ahydrocarbon containing fluid. Preferably, the ratio of CO to hydrogen inthe synthesis gas is adjusted to a value between 1:1 and 1:3,specifically to a value of 1:2.1.

In the method for generating synthetic functionalised and/ornon-functionalised hydrocarbons, at first a synthesis gas is generatedas described above, and the synthesis gas is brought into contact with asuitable catalyst in order to cause a conversion of the synthesis gasinto synthetic functionalised and/or non-functionalised hydrocarbons,wherein the temperature of the catalyst and/or the synthesis gas is(open loop) controlled or (close loop) regulated to a predefinedtemperature range. In this way, the synthesis gas may be generated bymixing CO with hydrogen, either before or upon bringing it into contactwith the catalyst.

In one embodiment, the conversion of the synthesis gas is performed by aFischer-Tropsch process, specifically a SMDS process. Alternatively, theconversion of the synthesis gas may be performed by a Bergius-Pierprocess, a Pier process or a combination of a Pier process with a MtLprocess (MtL=methanol to liquid). It is the choice of the process, whichlargely determines the nature of the synthetic functionalised and/ornon-functionalised hydrocarbons.

Preferably, the hydrocarbon containing fluid to be decomposed is naturalgas, methane, wet gas, heavy oil, or a mixture thereof.

The apparatus for converting carbon dioxide CO₂ into carbon monoxide COcomprises a hydrocarbon converter for decomposing a hydrocarboncontaining fluid into carbon and hydrogen, wherein the hydrocarbonconverter comprises at least one process chamber having at least oneinlet for a hydrocarbon containing fluid and at least one outlet forcarbon and/or hydrogen and at least one unit for introducing energy intothe process chamber, the energy consisting at least partially of heat.Further the apparatus comprises a CO₂ converter for converting CO₂ intoCO, the CO₂ converter comprising at least one additional process chamberhaving at least one inlet for CO₂, at least one inlet for at leastcarbon and at least one outlet, wherein the inlet for at least carbon isdirectly connected to the at least one outlet of the hydrocarbonconverter. Here, the term “directly connected” describes that carboncoming out of the hydrocarbon converter does not cool down by more than50% of its temperature in ° C., preferably not more than 20%, on its wayto the CO₂ converter without the utilisation of additional energy toheat up the carbon. A separating unit, which separates the carbon fromthe hydrogen, may be provided between the location of the decomposingstep and the at least one exit of the hydrocarbon converter. Thisseparating unit may form a part of hydrocarbon converter or may belocated outside the hydrocarbon converter as a separate unit. Aseparating unit between the exit of the hydrocarbon converter and theentrance of a C converter does not compromise a direct connection aslong as the above condition is met.

Preferably, the at least one unit for introducing energy into theprocess chamber is constructed in such a way that it is able to at leastlocally generate temperatures above 1000° C., specifically above 1500°C. In one embodiment, the at least one unit for introducing energy intothe process chamber is a plasma unit. Particularly, if the decomposingtemperature shall be kept below 1000° C., the at least one unit forintroducing energy into the process chamber preferably comprises amicrowave plasma unit.

For a particularly simple embodiment of the apparatus, the processchamber of the CO₂ converter is formed by an outlet pipe of thehydrocarbon converter which is connected to a supply pipe for CO₂ gas.

In one embodiment of the invention, a separation unit for separating thecarbon and the hydrogen generated by decomposing is provided in thevicinity of the hydrocarbon converter, and separate outlets from theseparation unit are provided for the separated materials, wherein theoutlet for carbon is connected to the CO₂ converter.

Preferably, the hydrocarbon converter is a Kvaerner reactor that canprovide the necessary temperatures for a continuous decomposing of ahydrocarbon containing fluid for long operating periods.

The apparatus for generating synthesis gas comprises an apparatus of thepreviously described type as well as at least one separate supply pipefor supplying hydrogen into the CO₂ converter or a downstream mixingchamber. Such an apparatus enables a simple and efficient generation ofa synthesis gas from CO₂ and hydrocarbon containing fluid.

In one embodiment, the apparatus for generating synthesis gas comprisesat least one additional hydrocarbon converter for decomposing ahydrocarbon containing fluid into carbon and hydrogen. The at least oneadditional hydrocarbon converter again comprises at least one processchamber having at least one inlet for the hydrocarbon containing fluid,at least one unit for introducing energy into the process chamber,wherein the energy at least partly consists of heat, and a separationunit for separating the carbon and the hydrogen, which were obtained bydecomposing, with the separation unit having separate outlets for carbonand hydrogen, wherein the outlet for hydrogen is connected to theseparate supply pipe for hydrogen. For reasons of energy efficiency, theat least one additional hydrocarbon converter is preferably of the typethat carries out decomposing at temperatures below 1000° C.,specifically below 600° C., by means of a microwave plasma.

The apparatus for converting a synthesis gas into syntheticfunctionalised and/or non-functionalised hydrocarbons comprises anapparatus for generating synthesis gas of the above specified type and aCO converter. The CO converter comprises a process chamber equipped witha catalyst, means for bringing the synthesis gas into contact with thecatalyst and a control unit for (open loop) controlling or (close loop)regulating the temperature of the catalyst and/or the synthesis gas to apredetermined temperature. In this way, parts of the apparatus forgenerating synthesis gas may be integrated into the CO converter, e.g. amixing chamber for CO and additional hydrogen. In one embodiment, the COconverter comprises a Fischer-Tropsch converter, particularly a SMDSconverter. Alternatively, the CO converter may comprise a Bergius-Pierconverter, a Pier converter or a combination of a Pier converter and aMtL converter. It is also possible that several CO converters of thesame type or of different types are provided in the apparatus.

Preferably, the apparatus comprises a control unit for controlling orregulating the pressure of the synthesis gas inside the CO converter.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention is explained in more detail with reference tocertain embodiments and drawings, wherein

FIG. 1 is a schematic representation of a plant for generating carbonmonoxide;

FIG. 2 is a schematic representation of a plant for generating synthesisgas;

FIG. 3 is a schematic representation of a plant for generatingfunctionalised and/or non-functionalised hydrocarbon;

FIG. 4 is a schematic representation of another plant for generatingfunctionalised and/or non-functionalised hydrocarbons according toanother embodiment;

FIG. 5 is a schematic representation of a plant for generatingfunctionalised and/or non-functionalised hydrocarbons according toanother embodiment;

FIG. 6 is a schematic representation of a plant for generatingfunctionalised and/or non-functionalised hydrocarbons according toanother embodiment;

FIG. 7 is a schematic representation of a plant for generating synthesisgas according to another embodiment; and

FIG. 8 is a schematic representation of a plant for generatingfunctionalised and/or non-functionalised hydrocarbons according toanother embodiment.

DESCRIPTION OF EMBODIMENTS

It shall be noted the terms top, bottom, right and left as well assimilar terms in the following description relate to the orientationsand arrangements, respectively, shown in the figures and are only meantfor the description of the embodiments. These terms are not limiting.Further, in the different figures, the same reference numerals are usedfor describing the same or similar parts.

In the following description, processes and apparatuses are describedthat handle “hot” materials or carry out “hot” processes. In the contextof this description, the expression “hot” shall describe a temperatureabove 200° C. and preferably above 300° C.

FIG. 1 schematically shows a plant 1 for converting carbon dioxide tocarbon monoxide. FIG. 1 also clarifies the basic process steps forconverting carbon dioxide to carbon monoxide according to thisdescription.

Plant 1 comprises a hydrocarbon converter 3 that comprises a hydrocarboninlet 4 and a first carbon outlet 5, an optional hydrogen outlet 6 aswell as an optional second carbon outlet 7. Plant 1 for generatingcarbon monoxide further comprises a CO₂ converter 9 having a CO₂ inlet10, a carbon outlet 11 (also referred to as C inlet) and an outlet 12.The hydrocarbon converter 3 and the CO₂ converter 9 are arranged suchthat the carbon outlet 5 of the hydrocarbon converter 3 is connected tothe carbon inlet 11 of the CO₂ converter 9 via a direct connection 8,wherein the outlet 5 may directly define the carbon inlet 11 of the CO₂converter 9. In this way, carbon may be directly transported from thehydrocarbon converter 3 into the CO₂ converter 9.

The hydrocarbon converter 3 is any hydrocarbon converter that canconvert or decompose introduced hydrocarbons into carbon and hydrogen.The hydrocarbon converter 3 comprises a process chamber having an inletfor a hydrocarbon containing fluid, at least one unit for introducingdecomposing energy into the fluid and at least one outlet. Thedecomposing energy is provided at least partially by heat, which is forinstance provided by a plasma. Nevertheless, the decomposing energy mayalso be provided by other means and, if decomposing is primarilyeffected by heat, the fluid should be heated to above 1000° C. andparticularly to a temperature above 1500° C.

In the described embodiment, a Kvaerner reactor is used, which providesthe required heat by means of a plasma arc and a plasma torch. However,other reactors are known, which operate at lower temperatures,particularly below 1000° C., and introduce additional energy besidesheat into the hydrocarbon, e.g. by means of a microwave plasma. As isfurther explained below, the invention considers both types of reactors(and also those which operate without plasma), in particular also bothtypes of reactors in combination with each other. Hydrocarbon convertersoperating at a temperature above 1000° C. are referred to as hightemperature reactors, whereas those converters operating at temperaturesbelow 1000° C., particularly at temperatures between 200° C. and 1000°C., are referred to as low temperature reactors.

Within the hydrocarbon converter, hydrocarbons (C_(n)H_(m)) aredecomposed into hydrogen and carbon by means of heat and/or a plasma.These hydrocarbons are preferably introduced into the reactor as gases.Hydrocarbons that are liquids under standard conditions may be vaporisedprior to introduction into the reactor or they may be introduced asmicro-droplets. Both forms are referred to as fluids in the following.

Decomposing of the hydrocarbons should be done, if possible, in theabsence of oxygen in order to suppress the formation of carbon oxides orwater. Nevertheless, small amounts of oxygen, which might be introducedtogether with the hydrocarbons, are not detrimental for the process.

The Kvaerner reactor described above decomposes hydrocarbon containingfluids in a plasma burner at high temperatures into pure carbon (forinstance as activated coal, carbon black, graphite or industrial soot)and hydrogen and, possibly, impurities. The hydrocarbon containingfluids used as starting material for the hydrocarbon converter 3 are forinstance methane, natural gas, biogases, wet gases or heavy oil.However, synthetic functionalised and/or non-functionalised hydrocarbonsmay also be used as starting material for the hydrocarbon converter 3.After the initial decomposing step, the elements are usually present asa mixture, particularly in form of an aerosol. This mixture may, asdescribed below, be introduced into another process in this form, or themixture may be separated into its individual elements in a separationunit, which is not shown. In the context of this application, such aseparation unit is considered as part of the hydrocarbon converter 3,although the separation unit may be constructed as a separate unit. Ifno separation unit is provided, the carbon outlet 5 is the only outletof the hydrocarbon converter 3 and directs a mixture (an aerosol) ofcarbon and hydrogen directly into the CO₂ converter 9. If the separationunit is provided, carbon, which is at least partially separated fromhydrogen, may be directed into the hydrocarbon converter 9 using thecarbon outlet 5. Separated hydrogen and, possibly, additional carbon maybe discharged by means of the optional outlets 6 and 7.

The CO₂ converter 9 may be any suitable CO₂ converter that can generatecarbon monoxide (CO) from carbon (C) and carbon dioxide (CO₂). In theembodiment of FIG. 1, the CO₂ converter 9 operates according to a partof a known reaction in a blast furnace, wherein said part reaction takesplace at temperatures between about 750° C. and 1200° C. without thenecessity of a catalyst. Preferably, the CO₂ converter operates at atemperature between 800° C. and 1000° C., wherein the heat required toreach that temperature primarily is provided by the exit material of thehydrocarbon converter 3, as will be described below in more detail. Inthe CO₂ converter 9, CO₂ is directed over hot carbon or is mixed withhot carbon (and possibly hydrogen) so as to be converted according tothe chemical reaction CO₂+C→2CO. The CO₂ converter 9 operates best atthe Boudouard equilibrium and at a temperature of 1000° C. Attemperatures of around 800° C., about 94% carbon monoxide will beprovided, and at temperatures of around 1000° C., around 99% carbonmonoxide will be provided. A further increase in temperature does notresult in significant changes.

The operation of plant 1 for converting carbon dioxide into carbonmonoxide is described in more detail below, with reference to FIG. 1. Inthe following, it is assumed that the hydrocarbon converter 3 is a hightemperature (HT) reactor of the Kvaerner type. Hydrocarbon containingfluids (specifically in gaseous form) are introduced into thehydrocarbon converter 3 via the hydrocarbon inlet 4. If the hydrocarbonis for instance methane (CH₄), then 1 mol carbon and 2 mol hydrogen willbe produced from 1 mol methane. The hydrocarbons are decomposed at about1600° C. in the hydrocarbon converter 3 according to the followingreaction equation, wherein the introduced energy is heat that isgenerated in the plasma by means of electric energy:

C_(n)H_(m)+Energy→nC+m/2H₂

With appropriate process control, the Kvaerner reactor is capable toconvert almost 100% of the hydrocarbons into their components in acontinuous operation.

In the following, it is assumed that the carbon and the hydrogen areseparated in the hydrocarbon converter 3 and that carbon and hydrogenwill be discharged largely separated. However, it is also possible thatseparation does not occur but carbon and hydrogen will be discharged andintroduced into the CO₂ converter 9 as a mixture. The hydrogen does notcompromise the conversion process in the CO₂ converter 9, but may serveas an additional heat transfer substance. The carbon is at leastpartially directed directly via the carbon outlet 5 into the carboninlet 11 of the CO₂ converter 9. The term “directly” directing fromoutlet 5 of the hydrocarbon converter 3 to the carbon inlet 11 of theCO₂ converter 9 shall include all embodiments wherein the directedmaterials do not experience a cooling down of more than 50% of thetemperature (preferably not more than 80% (annotation of the translator:obviously it was meant to be 20%, i.e. 80% residualenergy/temperature—see next paragraph). Since the carbon that exits fromthe hydrocarbon converter 3 has a high temperature, preferably over1000° C., the heat energy contained therein may be used to maintain thetemperature necessary for the conversion process in the CO₂ converter 9,which preferably operates at a temperature of about 1000° C.

The connection 8 between the hydrocarbon converter 3 and the CO₂converter 9 is designed such that the carbon does not cool down much(less than 50%, preferably less than 20% with respect to thetemperature) on its way from the hydrocarbon converter 3 to the CO₂converter 9. For instance, the connection 8 may be specially insulatedand/or actively heated, wherein the system is preferably not providedwith additional heat—i.e. not in addition to the heat introduced in thehydrocarbon converter 3. The hydrogen generated in the hydrocarbonconverter 3 also contains heat energy because of the operatingtemperature in the hydrocarbon converter 3. Therefore, one possibilityfor heating the connection 8 is to use the heat energy of the hydrogenthat exits through the hydrogen outlet 6 to heat the connection 8between the hydrocarbon converter 3 and the CO₂ converter 9 eitherdirectly or indirectly via a heat exchanger unit.

In the CO₂ converter, CO₂, which is introduced through the CO₂ inlet 10of the CO₂ converter 9, is directed over hot carbon and/or is mixed withhot carbon. The CO₂ converter operates best at the Boudouardequilibrium, which occurs during the reaction of carbon dioxide with hotcarbon. The reaction, which is known to the person skilled in the art,depends on pressure and temperature and will not be described in detail.Either the amount of the CO₂ or the amount of carbon introduced into theCO₂ converter 9 may be (open loop) controlled and/or (close loop)regulated by appropriate means.

CO₂+C→2CO ΔH=+172.45 kJ/mol

The CO₂ may originate e.g. from a power plant (coal, gas and/or oiloperated) or from another industrial process (e.g. steel or cementproduction) generating appropriate amounts of CO₂. Depending on thetemperature of the CO₂ from the CO₂ source, it is advantageous topreheat the CO₂ introduced into the CO₂ inlet 10 of the CO₂ converter 9,as the CO₂ converter 9 operates at a temperature between 800 and 1200°C. Preheating of the CO₂ may be achieved e.g. by using the heat energycontained in the hot hydrogen either directly or indirectly via a heatexchange unit to preheat the CO₂. Preferably, the heat contained in thecarbon is sufficient to heat the CO₂ to the desired temperature. Only inthe case where the heat generated in the hydrocarbon converter 3 is notsufficient to reach the desired conversion temperature of about 1000°C., an optional additional heating unit for heating the CO₂ converter 9or elements contained therein may be provided. Such a unit may also beprovided as a preheating unit in the vicinity of a supply line for CO₂or carbon. Such a unit may also be provided only for the start-up phaseof the plant in order to bring the CO₂ converter 9 or media containingparts of the plant to a starting temperature so that the system canfaster reach a desired temperature state. Heating of all mediacontaining parts exclusively via the heat generated in the hydrocarbonconverter 3 might take too long in the beginning.

Hot carbon monoxide (CO) having a temperature of about 800 to 1000° C.(depending on the operating temperature of the CO₂ converter 9) exitsfrom the CO₂ converter 9. The carbon monoxide that exits from the CO₂converter 9 also contains heat energy, which may be used e.g. to preheatthe CO₂ introduced into the CO₂ inlet 10, either directly or indirectlyvia a heat exchange unit (not shown in FIG. 1).

As mentioned above, the hydrocarbon converter 3 may comprise a secondcarbon outlet 7 to discharge carbon. The carbon generated in thehydrocarbon converter 3 may be discharged—after a respective separationstep (or as a C—H₂ mixture)—in different proportions through the firstcarbon outlet 5 and the second carbon outlet 7. The second carbon outlet7 is used to discharge a portion of the generated carbon that is notused in the CO₂ converter 9 to generate carbon monoxide. The carbondischarged through the second carbon outlet 7 may be discharged asactivated carbon, graphite, carbon black or another modification such ascarbon cones or carbon discs. Depending on the form and the quality ofthe discharged carbon, the discharged carbon may be used as raw materialfor the chemical industry or the electronics industry. Possibleapplications are for instance the manufacture of semiconductors, theproduction of tires, inks, toner or similar products. The carbongenerated by the hydrocarbon converter 3 is a highly pure raw materialthat can be processed very well.

By means of the method described above for converting carbon dioxideinto CO, it is possible to convert the hot carbon from the hydrocarbonconverter 9 in the CO₂ converter 9 with warm or hot carbon dioxide fromthe exhaust gas from industrial processes to CO without or at leastwithout significant external energy supply. Preferably, at least 80%,specifically at least 90%, of the heat necessary to reach the conversiontemperature should originate from the hydrocarbon converter 3.

FIG. 2 shows a plant 20 for generating synthesis gas that comprises theabove described elements of plant 1 for generating carbon monoxide aswell as a mixing chamber 21, the mixing chamber 21 comprising a CO inlet22 for introducing carbon monoxide and a H₂ inlet 23 for introducinghydrogen as well as a synthesis gas outlet 24 for discharging synthesisgas. The CO inlet 22 is connected to the CO outlet 12 of the CO₂converter 9. The H₂ inlet 23 of the mixing chamber 21 is connected tothe H₂ outlet 6 of the hydrocarbon converter 3. As is obvious to theskilled person, the embodiment, which introduces a C—H₂ mixture into theCO₂ converter 9 through the carbon outlet 5 automatically generates asynthesis gas having a mixing ratio of CO—H₂ of about 1:1. In such acase, the mixing chamber 21 may not be present, or the mixing chamber 21may be used to produce a different mixing ratio.

The mixing chamber 21 may be any suitable apparatus for mixing gasesand, in a simple case, the mixing chamber 21 may be in the form of apipe having suitable inlets and an outlet. By means of the mixingchamber 21 and specifically by means of controlling/regulating(open/closed loop) the amount of (additional) hydrogen introducedthrough the H₂ inlet 23 of the mixing unit 21, the mixture of thesynthesis gas at the synthesis gas outlet 24 may be influenced such thata composition can be achieved, which is suitable for subsequentprocesses.

For many processes, for instance the Fischer-Tropsch synthesis, theratio of hydrogen to CO should be high. By means of the mixing chamber21, any desired ratio of hydrogen to CO may be achieved at the synthesisgas outlet 24. It is considered that only a portion of the CO and/orpart of the hydrogen is introduced into the mixing chamber 21, whereasthose portions of CO and hydrogen that are not introduced into themixing chamber are each discharged from the process as pure gases.Therefore, it is for instance possible, a) to discharge only CO, b) todischarge only hydrogen, c) to discharge a synthesis gas mixture of COand hydrogen or d) to discharge a stream of CO, a stream of hydrogen anda stream of a synthesis gas mixture (CO+hydrogen).

Furthermore, the plant 20 for generating synthesis gas shown in FIG. 2comprises a first heat exchange unit 25, a second heat exchange unit 26and a third heat exchange unit 27. The first heat exchanger unit 25 isin thermally conductive contact with the connection 8 between thehydrocarbon converter 3 and the CO₂ converter 9 and is adapted to, ifnecessary, extract surplus heat not required to reach the conversiontemperature in the CO₂ converter 9 from the connection or to introduceheat from other areas of the plant, if necessary.

The second heat exchanger unit 26 is in thermally conductive contactwith the connection between the CO₂ converter 9 and the mixing chamber21 and is adapted to extract surplus heat from the connection and thusto extract surplus heat contained in the hot CO. This surplus heat maybe used e.g. to preheat the CO₂ that is introduced into the CO₂converter 9. For this heat transfer a so-called counter flow heatexchanger unit as known in the art would be particularly suitable.

The third heat exchanger unit 27 is in thermally conductive contact withthe connection between the hydrocarbon converter 3 and the mixingchamber 21 and is adapted to extract surplus heat from the connectionand thus from the hot hydrogen contained therein. The heat extracted atone of the first, second or third heat exchanger units may be used toheat other areas of the plant, specifically to keep the CO₂ converterwarm or to preheat the CO₂ that is introduced into the CO₂ converter. Aportion of the heat may be converted into electricity, for instance by asteam generator and a steam turbine or by another suitable apparatus.

The operation of plant 20 for generating synthesis gas is, with respectto the operation of the hydrocarbon converter 3 and the CO2 converter 9,similar to the above described operation of plant 1 according to FIG. 1.In plant 20 for generating synthesis gas, a desired mixing ratio ofhydrogen to CO is set in the mixing chamber and is discharged throughthe synthesis gas outlet 24 of the mixing chamber, depending on thedesired composition of the synthesis gas. Preferably, but notnecessarily, the hydrogen is provided by the hydrocarbon converter 3, aswas described. Other hydrogen sources may be considered, particularly asecond hydrocarbon converter 3, particularly a low temperaturehydrocarbon converter. If not the entire available amount of CO and/orthe entire available amount of H₂ are used, those parts of the gases COand H₂ that are not mixed in the mixing chamber may be processedseparately.

FIG. 3 shows a plant 30 for generating synthetic functionalised and/ornon-functionalised hydrocarbons that comprises a plant 1 for convertingcarbon dioxide into carbon monoxide (as shown in FIG. 1) and a COconverter 31. Those parts of the plant corresponding to plant 1 are notexplained in detail in order to avoid repetitions. The CO converter 31is located downstream from the CO₂ converter 9 and comprises a CO inlet32 for introducing CO, a H₂ inlet 33 for introducing hydrogen and ahydrocarbon outlet 34 for discharging synthetic functionalised and/ornon-functionalised hydrocarbons. The CO inlet 32 of the CO converter 31is connected to the CO outlet 12 of the CO2 converter 9 by means of theCO connection 35. The H₂ inlet 33 of the CO converter 31 is connected tothe H₂ outlet 6 of the hydrocarbon converter 3 by means of the H₂connection 36.

The plant 30 for generating hydrocarbons optionally also comprises theheat exchanger units 25, 26, 27 described in conjunction with plant 20(FIG. 2), wherein all of these operate in the above described way (seedescription to FIG. 2).

The CO converter 31 may be any CO converter for generating syntheticfunctionalised and/or non-functionalised hydrocarbons. In the embodimentshown in FIG. 3, the CO converter is preferably a Fischer-Tropschconverter, a Bergius-Pier converter or a Pier converter with a suitablecatalyst and a control unit for temperature and/or pressure.

In one embodiment, the CO converter 31 comprises a Fischer-Tropschconverter. A Fischer-Tropsch converter catalytically converts asynthesis gas into hydrocarbons and water. Several embodiments ofFischer-Tropsch reactors and Fischer-Tropsch processes are known to theperson skilled in the art and are not explained in detail. The mainreaction equations are as follows:

nCO+(2n+1)H₂→C_(n)H_(2n+2) +nH₂O for alkanes

nCO+2nH₂→C_(n)H_(2n) +nH₂O for alkenes

nCO+2nH₂→C_(n)H_(2n)+1OH+(n−1)H₂O for alcohols

The Fischer-Tropsch processes may be carried out as high temperatureprocesses or as low temperature processes, wherein the processtemperatures are usually in the range of 200 to 400° C. Known variantsof the Fischer-Tropsch process are, among others, the Hochlastsynthesis, the Synthol synthesis and the SMDS process of Shell(SMDS=Shell Middle Distillate Synthesis). A Fischer-Tropsch convertertypically produces a hydrocarbon compound of wet gases (propane,butane), petrol, kerosene, soft paraffin, hard paraffin, methanol,methane, Diesel fuel or a mixture of several of these. It is known tothe person skilled in the art that the Fischer-Tropsch synthesis isexothermic. The heat of reaction from the Fischer-Tropsch process may beused e.g. by means of a heat exchanger unit (not shown in the figures)to preheat the CO₂. As an example, a two-step preheating process for theCO₂ to be introduced into the CO₂ converter 9 is considered, wherein afirst preheating step is realised with the surplus heat of the COconverter 31 (in the embodiment of a Fischer-Tropsch converter) andsubsequently a step of further heating of the CO₂ by means of the heatfrom one or more of the heat exchanger units 25, 26, 27.

In an alternative embodiment, the CO converter 31 comprises aBergius-Pier converter or a combination of a Pier converter with a MtLconverter (MtL=Methanol-to-Liquid).

In a Bergius-Pier reactor, the Bergius-Pier process, which is well knownto a person skilled in the art, is carried out, wherein hydrocarbons aregenerated by hydrogenation of carbon with hydrogen in an exothermicchemical reaction. The range of products from the Bergius-Pier processdepends on the reaction conditions and control of the reaction process.Mainly liquid products are obtained, which may be used as transportationfuels, for instance heavy and medium oils. Known variants of theBergius-Pier process are for instance the Konsol process and the H-Coalprocess.

In the above mentioned combination of a Pier converter with a MtLconverter, at first synthesis gas is converted into methanol accordingto the Pier process. The MtL converter is a converter that convertsmethanol into petrol. A widespread process is the MtL process ofExxonMobil respectively Esso. Starting material of the MtL converter istypically methanol, for instance from the Pier converter. The exitproduct generated by the MtL converter typically is petrol, which issuitable for the operation of an Otto engine.

It may be summarized that the CO converter 31, regardless of theoperating principles explained above, generates synthetic functionalisedand/or non-functionalised hydrocarbons from CO and H₂ as its output orend products. By means of a heat exchanger unit, the process heatproduced during the exothermic conversion in the CO converter 31, may beused to heat different sections of the plant or to generate electricityin order to increase the efficiency of the described plant.

As far as a mixture of hydrocarbons, which cannot be further processeddirectly or sold profitably as a final product after separation andspecification, is obtained as exit products of the CO converter 31,these hydrocarbons, for instance methane or short-chain paraffins, maybe recycled into the process described above. For this purpose, theplant 30 comprises a recycle connection 39, which can direct a portionof the synthetically generated hydrocarbons back to the hydrocarboninlet 4 of the hydrocarbon converter 3. Depending on the composition ofthe recycled, synthetically generated hydrocarbons, a treatment orseparation step of unsuitable hydrocarbons is carried out prior tointroducing the unsuitable hydrocarbons into the hydrocarbon inlet 4.

FIG. 4 shows a further embodiment of a plant 40 for generating syntheticfunctionalised and/or non-functionalised hydrocarbons. The plant 40comprises the above described plant 20 for generating a synthesis gas aswell as a CO converter 31 as described above with reference to theembodiment in FIG. 3. The synthesis gas outlet 24 of the mixing chamber21 is connected to the CO converter 31. The mixing chamber 21 is set insuch a way that it provides a synthesis gas specifically adapted to theneeds of the CO converter 31 in use at the synthesis gas outlet 24. Theother elements of plant 40 are the same as described above and theoperation of the individual elements essentially takes place in the waydescribed above.

It is considered that, depending on the size of the plant, a pluralityof hydrocarbon converters are operated in parallel in order to providethe desired conversion capacity. As mentioned above, the hydrocarbonconverters may be constructed as high temperature hydrocarbon convertersand/or as low temperature hydrocarbon converters. A high temperaturehydrocarbon converter operates at temperatures above 1000° C. and a lowtemperature hydrocarbon converter operates at temperatures between 200and 1000° C., wherein an additional source of energy, for instance amicrowave unit, may be provided in order to achieve decomposition of thehydrocarbon into carbon and hydrogen.

As an example for a plant with a plurality of parallel operatedhydrocarbon converters, FIG. 5 shows a further embodiment of plant 30for generating synthetic functionalised and/or non-functionalisedhydrocarbons. FIG. 5 uses the same reference numerals as in earlierembodiments, as far as the same or similar elements are described. Inthe embodiment shown in FIG. 5, a combination of a high temperaturehydrocarbon converter 3 a and a low temperature hydrocarbon converter 3b is shown instead of a single hydrocarbon converter 3.

The high temperature hydrocarbon converter 3 a comprises a hydrocarboninlet 4 a, a first outlet 5 a to discharge carbon and a second outlet 6a to discharge hydrogen. Again, a single outlet 5 a may be provided fora mixture (particularly an aerosol) of carbon and hydrogen. The outlet 5a is connected to the inlet 11 of the CO2 converter 9 by a connection 8.The optional outlet 6 a of the high temperature hydrocarbon converter 3a is connected to the H2 inlet 33 of the CO converter 31. The hightemperature hydrocarbon converter 3 a may optionally comprise a furtheroutlet for carbon (not shown in FIG. 5).

The low temperature hydrocarbon converter 3 b comprises a processchamber having a hydrocarbon inlet 4 b, a first outlet 5 b to divertcarbon, a second outlet 6 b for discharging hydrogen and an optionalthird outlet 7 b for discharging carbon. Preferably, the low temperaturehydrocarbon converter 3 b comprises a separation unit for separatinghydrogen and carbon after decomposition and for directing the hydrogenand carbon to their respective outlets. The first outlet 5 b isoptionally connected to inlet 11 of the CO₂ converter 9 via connection8, but may also be connected to a carbon collection unit. The outlet 6 bof the low temperature hydrocarbon converter 3 b is connected to the H₂inlet 33 of the CO converter 31. The optional third outlet 7 b isconnected to a carbon collection unit from which collected carbon may bewithdrawn, for instance as carbon black, activated coal or in anotherform.

The hydrocarbon introduced into the hydrocarbon inlet 4 a and thehydrocarbon introduced into the hydrocarbon inlet 4 b may be the samehydrocarbon or may be different hydrocarbons. A hydrocarbon from a firsthydrocarbon source may be introduced into the hydrocarbon inlet 4 a, forinstance natural gas from a natural gas source. However, e.g.functionalised and/or non-functionalised, synthetically generatedhydrocarbon may be introduced into the hydrocarbon inlet 4 b of the lowtemperature hydrocarbon converter 3 b, for instance via the earliermentioned optional recycle connection 39. Because of the utilisation ofseveral parallel operated hydrocarbon converters 3 a, 3 b, the plant 30may be scaled easier, may be controlled easier, and different kinds ofcarbon may be produced.

Furthermore, the high temperature hydrocarbon converter 3 a may forinstance be used advantageously to generate “hot” carbon, preferably ata temperature over 1000° C., for the CO₂ conversion process in the CO₂converter 9. In particular, the high temperature hydrocarbon converter 3a may operate in this case without a separation unit, since the C—H₂mixture, obtained by decomposing, may be introduced directly into theCO₂ converter. In this case, the CO₂ converter 9 produces a synthesisgas having a C—H₂ mixing ratio of e.g. about 1:1 at the outlet.

The low temperature hydrocarbon converter 3 b, however, is primarilyused in order to provide additional hydrogen for the generation of asynthesis gas or a C—H₂ mixture having a C—H₂ mixing ratio of greaterthan 1:1, in particular greater than 1:2 in the CO converter 31. As noheat transfer from the low temperature hydrocarbon converter 3 b to asubsequent process is necessary, the low temperature hydrocarbonconverter 3 b may advantageously be operated at temperatures below 1000°C. and preferably at the lowest possible temperature.

Thus, a portion of the carbon produced in the hydrocarbon converters 3a, 3 b (preferably the portion from the high temperature hydrocarbonconverter 3 a) may be introduced into the CO₂ converter 9 during theoperation of plant 30, whereas another portion (preferably the portionfrom the low temperature hydrocarbon converter 3 b) may be dischargedfrom the process as raw material for producing further products. Suchproducts are for instance carbon black or industrial soot, activatedcoal, special kinds of carbon such as carbon discs and carbon conesetc., which is obtained as black powdery solid matter. This carbon is animportant technical product, which may be used e.g. as filler in therubber industry, as pigment soot for printing colours, inks, paints oras starting material for the generation of electrical components, forinstance zinc-carbon-batteries and for the production of cathodes oranodes. Any surplus hydrogen may be discharged for the chemical industryor may be used for generating electricity (by burning), whereby the lowtemperature hydrocarbon converter 3 b is preferably operated in such away that it only provides the necessary additional hydrogen.

FIG. 6 shows an alternative embodiment of the above described plant 40for generating synthetic functionalised and/or non-functionalisedhydrocarbons, for which a plurality of parallel operated hightemperature and/or low temperature hydrocarbon converters are providedas well.

The plant 40 for generating hydrocarbons shown in FIG. 6 differs fromthe plant 30 shown in FIG. 5 in such a way that a mixing chamber 21 islocated upstream of the CO converter 31. The mixing chamber 21 mixes asynthesis gas specifically adapted to the CO converter 31 and providesthe synthesis gas to the CO converter 31. The elements depicted in FIG.6 have already been described above and work according to the principlesdescribed above. Therefore, no detailed description is given in order toavoid repetitions.

FIGS. 7 and 8 show embodiments of the plants 20 and 30 comprising afirst heat exchanger unit 25, a second heat exchanger unit 26 and athird heat exchanger unit 27, wherein each is connected to anengine/generator device 45. The engine/generator device 45 is adapted toat least partially generate electricity from surplus heat from differentsections of the plant, wherein said electricity may either be fed intothe main grid or may be used to operate the plant 20, especially thehydrocarbon converter(s). Further, the engine/generator device 45 may beconnected to a heat exchanger unit (not shown in FIG. 8), whichdissipates the heat generated by the exothermic conversion processtaking place inside the CO converter 31. Thus, on the one hand the COconverter may be cooled in a controlled and regulated way, which isadvantageous for the operation of the process, and on the other handelectricity may be generated. The engine/generator device 45 may be anydevice that is adapted to transform heat energy into electricity, forinstance a combination of a steam turbine and a generator or a pistonengine and a generator.

During operation, the engine/generator device 45 transforms the surplusheat of the plant into electricity, i.e. the heat that is not necessaryfor CO₂ conversion.

The engine/generator device 45 and the heat exchanger units 25, 26 and27 are optional elements that may be used at all plants described above.Due to the operation temperature in the respective hydrocarbon converter3, 3 a, 3 b, the carbon discharged from the respective second outlets 7,7 a, 7 b also contains significant amounts of heat energy. Depending onthe desired temperature of the discharged carbon, a large amount of thisheat energy may be dissipated by means of heat exchanger units (notshown in the figures) and the heat may be reused in the processesdescribed herein and/or may be transformed into electricity using theengine/generator device 45.

In the plants 30 and 40 for generating synthetic functionalised and/ornon-functionalised hydrocarbons, cooling of the hydrogen from thehydrocarbon converters 3, 3 a, 3 b and/or cooling of the CO from the CO₂converter 9 is performed only as far as the temperature of thehydrocarbons and of the hydrogen does not fall below the operatingtemperature of the CO converter 31. The operating temperature of the COconverter 31 is usually between 200 and 400° C., depending on the chosenprocess.

In all plants described above, the hydrocarbon converter 3 may be a hightemperature reactor operating at a temperature of more than 1000° C.(e.g. a high temperature Kvaerner reactor) or a low temperature reactoroperating at a temperature between 200° C. and 1000° C. (e.g. a lowtemperature Kvaerner reactor). A presently tested low temperaturereactor operates at temperatures between 300 and 800° C. In the case ofa low temperature reactor operating at temperatures between 200 and 800°C., it is considered that the introduced carbon is preheated in theconnection 8 between the hydrocarbon converter 3 and the CO₂ converter9, as the CO₂ converter 9 operates at temperatures between 800 and 1000°C. Further, it becomes clear from FIGS. 7 and 8 that a combinationbetween high temperature and/or low temperature converters may be usedin all plants 1, 20, 30 and 40 described above.

In all plants 1, 20, 30 and 40 described above, a portion of the carbongenerated in the hydrocarbon converters 3, 3 a, 3 b may be discharged ascarbon black, as activated coal or as another raw material as long assaid carbon is not converted in the CO₂ converter 9 of plant 1, 20, 30,40. It shall further be noted that also a portion of the hydrogenproduced in the hydrocarbon converter 3 may be directly discharged outof the process and may be sold as commodity. Further, undesiredsynthetic functionalised and/or non-functionalised hydrocarbonsgenerated in the CO converter 31 may be returned and fed into thehydrocarbon inlets 4, 4 a, 4 b of the hydrocarbon converter 3 in allplants 30 and 40 described above.

It is considered that the CO₂ introduced into the CO₂ converter 9 is aexhaust gas from a combustion power plant or that the CO₂ is generatedin another industrial process. Recently, emphasis is put on releasingsmaller amounts of CO₂ into the environment, as CO₂ is seen as a climatepollutant. In the above mentioned exhaust gases, the CO₂ is mixed withother gases including, amongst others, a large amount of nitrogen fromthe air. With none of the above described plants 1, 20, 30, 40 is itnecessary to separate the nitrogen prior to introducing the mixture ofCO₂ and other gases into the CO₂ converter 9. As far as these othergases are only present in small amounts or are chemically inert (e.g.nitrogen), the operation of the CO₂ converter 9 is not compromised bythe additional gases. A residual component of oxygen is burned in theCO₂ converter at the high operating temperature in presence of carbon.

Some examples follow for further clarification:

Example 1 CO₂ Neutral Gas Power Plant

By means of a Kvaerner reactor as the hydrocarbon converter 3, methaneis decomposed into carbon and hydrogen. For each atom of carbon, twomolecules of hydrogen will be obtained (CH₄→C+2H₂). Starting from aconventional natural gas power station, for instance of the typeIrsching IV, manufactured by Siemens AG, having a nominal capacity of561 MW, the CO₂ contained in the exhaust gas is introduced into the CO₂converter 9—about 1.5 million tons a year. The CO₂ from the exhaust gasof the natural gas power plant is reduced with half of the carbondischarged from the hydrocarbon converter 3. The hydrogen from thehydrocarbon converter 3 is cooled down and the dissipated heat istransformed into electricity by means of the engine/generator device 45.The CO₂ from the natural gas power plant is directed over hot carboninside the CO₂ converter 9 and is converted into twice the amount ofcarbon monoxide according to the Boudouard equilibrium (CO₂+C→2 CO). Thehot carbon monoxide exiting from the CO₂ converter 9 is cooled down, andthe dissipated heat is transformed into electricity. The carbon monoxidefrom the CO₂ converter 9 (Boudouard equilibrium) and the hydrogen fromthe hydrocarbon converter 3 (Kvaerner process) are converted in a COconverter 31 (Fischer-Tropsch plant) to form hydrocarbons. A HeavyParaffin Synthesis module connected to a subsequent Heavy ParaffinConversion module from the SMDS-process (=Shell Middle DistillateSynthesis process) manufactured by Shell is preferred. The heat from theprocess is transformed into electricity. The nature of the resultinghydrocarbons depends on the chosen Fischer-Tropsch process and may bevaried in the Shell SMDS process.

In the specific natural gas power plant (561 MW) having an efficiency of60.4%, assuming an efficiency of 60% when transforming the process heatinto electricity and assuming an efficiency of 50% when transformingdissipated heat into electricity, the process has the followingparameters:

Consumption of methane 2515 million S m³ CH₄ per year Generation ofelectricity 313 MW Carbon black production 447 000 tons per yearParaffin production 1.0 million tons per year CO₂ emission almost 0Efficiency natural gas power plant 33.7% Total 66.8%

Example 2 Gas-to-Liquid Plant

If the plant from example 1 is operated without transforming the processheat and the dissipated heat into electricity, then no significantamount of electricity is generated. In this case, the example is aprocess for converting gaseous materials (carbon dioxide and methane)into liquid fuels (Otto and Diesel fuels, kerosine), i.e. aGas-to-Liquid or GtL plant. In the present example, an additional amountof carbon is produced.

The parameters are as follows:

Consumption of methane 2515 million S m³ CH₄ per year Generation ofelectricity 0 MW Carbon black production 447 000 tons per year Paraffinproduction 1.0 million tons per year CO₂ emission almost 0

The invention has been explained in some detail with respect to specificembodiments and examples without being limited to these examples. Inparticular, the elements of the individual embodiments may be combinedand/or exchanged with each other, if compatible. The skilled person willbecome aware of manifold modifications and deviations within the scopeof the following claims. In a particularly simple embodiment of theplant for generating synthetic functionalised and/or non-functionalisedhydrocarbons, the CO₂ converter may be designed e.g. as a simple pipe(for instance as an outlet pipe of a high temperature hydrocarbonconverter not having a separation unit), wherein a CO₂ pipe leads tosaid pipe. The CO₂ pipe should join said pipe such that the two gasstreams get well mixed. The pipe should be insulated and could beconnected to a heating unit e.g. at an inlet section in order to heat upthe pipe (especially at the beginning of the operation) to an operatingtemperature. Further downstream, the pipe could be connected to a heatexchanger unit adapted to extract surplus heat and to use this heat forheating other sectors of the plant and/or for generating electricity.Additionally, the pipe may comprise an inlet pipe for hydrogen (forinstance downstream of the heat exchanger unit) so that the same pipenot only functions as a CO₂ converter, but also functions as a mixingchamber for generating a synthesis gas. The inlet pipe for hydrogen mayoriginate e.g. from an outlet for hydrogen of a low temperaturehydrocarbon converter (having a separation unit). In this case, anoutput end of the pipe, where a synthesis gas having a predeterminedmixing ratio may be discharged, could end in a CO converter.

1-31. (canceled)
 32. A method for converting carbon dioxide CO₂ intocarbon monoxide CO comprising the following steps: decomposing ahydrocarbon containing fluid into carbon and hydrogen by means ofintroduction of energy in a hydrocarbon converter, the energy at leastpartially being provided by heat, wherein the carbon and the hydrogenhave a temperature of at least 200° C. after the decomposing step;directing at least a portion of the carbon generated by the decomposingstep from the hydrocarbon converter into a CO₂ converter; introducingCO₂ gas from an external CO₂ source into the CO₂ converter; mixing theCO₂ gas with at least a portion of the carbon generated by thedecomposing step, wherein upon mixing the carbon with the CO₂ gas, thecarbon obtained by the decomposing step has cooled down by no more than50% in ° C. with respect to its temperature after the decomposing step;converting at least a portion of the CO₂ gas and the carbon obtained bythe decomposing step into CO at a temperature between 800 and 1700° C.33. The method for converting CO₂ into CO according to claim 1, whereinthe decomposing step takes place at a temperature above 1000° C., andwherein the carbon is mixed with the CO₂ gas at a temperature of atleast 800° C.
 34. The method for converting CO₂ into CO according toclaim 1, wherein the heat required to reach the temperature of between800 and 1700° C. for the CO₂ conversion originates essentiallycompletely from the heat that is provided for decomposing thehydrocarbon containing fluid.
 35. The method for converting CO₂ into COaccording to claim 1, wherein the carbon obtained by the decomposingstep and the hydrogen obtained by the decomposing step are jointly mixedwith the CO₂ gas.
 36. The method for converting CO₂ into CO according toclaim 1, wherein the carbon obtained by the decomposing step isseparated from the hydrogen obtained by the decomposing step prior tothe step of mixing the carbon with the CO₂ gas.
 37. The method forconverting CO₂ into CO according to claim 1, wherein at least a portionof the heat of at least one of a portion of the carbon obtained by thedecomposing step and a portion of the hydrogen obtained by thedecomposing step is used to one of heating the CO₂ gas prior to mixingthe CO₂ gas with carbon and heating the process chamber, in which theCO₂ gas is mixed with the carbon.
 38. The method for converting CO₂ intoCO according to claim 1, wherein the CO has a temperature of 800 to1700° C. after conversion, and wherein at least a portion of its heat isused to preheat the CO₂ gas prior to mixing with the carbon.
 39. Themethod for converting CO₂ to CO according to claim 1, wherein at least aportion of the heat of at least one of a portion of the carbon obtainedby the decomposing step and a portion of the hydrogen obtained by thedecomposing step and a portion of the CO, after conversion to CO, isused for generating electricity, wherein the electricity mayparticularly be provided as energy carrier for introducing energy fordecomposing the hydrocarbon containing fluid.
 40. The method forconverting CO₂ into CO according to claim 1, wherein the energy isprimarily introduced by means of a plasma.
 41. The method for convertingCO₂ into CO according to claim 1, wherein the decomposing step isperformed in a Kvaerner reactor.
 42. A method for generating a synthesisgas, wherein CO₂ is first converted into CO according to claim 1; andwherein hydrogen is mixed with the CO subsequently.
 43. The method forgenerating a synthesis gas according to claim 11, wherein the hydrogenis generated by decomposing a hydrocarbon containing fluid into carbonand hydrogen by introduction of energy that is at least partiallyprovided by heat.
 44. The method for generating a synthesis gasaccording to claim 12, wherein at least a portion of the hydrogen isgenerated by decomposing a hydrocarbon containing fluid at a temperaturebelow 1000° C., particularly below 600° C., by means of a microwaveplasma.
 45. The method for generating a synthesis gas according to claim11, wherein the ratio of CO to hydrogen of the synthesis gas has a valueof 1:1 to 1:3, particularly a value of about 1:2.1.
 46. A method forgenerating synthetic functionalised and/or non-functionalisedhydrocarbons, wherein at first a synthesis gas is generated according tothe method of claim 11, and wherein the synthesis gas is brought intocontact with a suitable catalyst in order to cause conversion of thesynthesis gas into at least one of synthetic functionalised andsynthetic non-functionalised hydrocarbons, wherein the temperature of atleast one of the catalyst and the synthesis gas is open-loop controlledor close-loop regulated to a predetermined range of temperature.
 47. Themethod for generating synthetic functionalised and/or non-functionalisedhydrocarbons according to claim 15, wherein the conversion of thesynthesis gas is carried out by means of one of the following: aFischer-Tropsch process, a SMDS process, a Bergius-Pier process, a Pierprocess or a combination of a Pier process and a MtL process.
 48. Themethod according to claim 1, wherein the hydrocarbon containing fluid tobe decomposed is natural gas, methane, wet gases, heavy oil or a mixturethereof.
 49. An apparatus for converting carbon dioxide CO₂ into carbonmonoxide CO comprising: a hydrocarbon converter for decomposing ahydrocarbon containing fluid into carbon and hydrogen, wherein thehydrocarbon converter comprises at least one process chamber having atleast one inlet for a hydrocarbon containing fluid and at least oneoutlet for at least one of carbon and hydrogen, and wherein thehydrocarbon converter comprises at least one unit for introducing energyinto the process chamber, the energy consisting at least partially ofheat; a CO₂ converter for converting CO₂ into CO, the CO₂ convertercomprising at least one further process chamber having at least oneinlet for CO₂ adapted to introduce CO₂ from an external CO₂ source intothe CO₂ converter, at least one inlet for at least carbon, and at leastone outlet, wherein the inlet for at least carbon is directly connectedto the at least one outlet of the hydrocarbon converter.
 50. Theapparatus for converting carbon dioxide CO₂ into CO according to claim18, wherein the at least one unit for introducing energy into theprocess chamber is designed in such a way that it can generate, at leastlocally, temperatures above 1000° C.
 51. The apparatus for convertingcarbon dioxide CO₂ into carbon monoxide CO according to claim 18,wherein the at least one unit for introducing energy into the processchamber comprises a plasma unit, particularly a microwave plasma unit.52. The apparatus for converting carbon dioxide CO₂ into carbon monoxideCO according to claim 18, wherein the process chamber of the CO₂converter is formed by an outlet pipe of the hydrocarbon converter,wherein the outlet pipe is connected to an inlet for CO₂ gas.
 53. Theapparatus for converting carbon dioxide CO₂ into carbon monoxide COaccording to claim 18, further comprising a separation unit forseparating the carbon obtained by decomposing and the hydrogen obtainedby decomposing and having separate outlets for the separated materialscoming from the separation unit, wherein the outlet for carbon isconnected to the CO₂ converter.
 54. The apparatus for converting carbondioxide CO₂ into carbon monoxide CO according to claim 18, wherein thehydrocarbon converter comprises a Kvaerner reactor.
 55. An apparatus forgenerating a synthesis gas comprising an apparatus according to claim 18and at least one separate inlet pipe for hydrogen leading into the CO₂converter or into a mixing chamber located downstream.
 56. The apparatusfor generating a synthesis gas according to claim 24 having at least oneadditional hydrocarbon converter for decomposing a hydrocarboncontaining fluid into carbon and hydrogen, the hydrocarbon convertercomprising: at least one process chamber having at least one inlet forthe hydrocarbon containing fluid; at least one unit for introducingenergy into the process chamber, the energy at least partiallyconsisting of heat; a separation unit for separating the carbon obtainedby decomposing and the hydrogen obtained by decomposing, the separationunit having separate outlets for carbon and hydrogen, wherein the outletfor hydrogen is connected to the separate inlet for hydrogen.
 57. Theapparatus for generating a synthesis gas according to claim 25, whereinthe at least one additional hydrocarbon converter is of a type carryingout decomposing at temperatures below 1000° C., particularly below 600°C. by means of a microwave plasma.
 58. An apparatus for converting asynthesis gas into synthetic functionalised and/or non-functionalisedhydrocarbons comprising: an apparatus according to claim 24; and a COconverter having a process chamber, in which a catalyst is located, andmeans for bringing the synthesis gas into contact with the catalyst, anda control unit open-loop controlling or close-loop regulating thetemperature of at least one of the catalyst and the synthesis gas to apredetermined temperature.
 59. The apparatus according to claim 27,wherein the CO converter comprises one of the following: aFischer-Tropsch converter, a SMDS converter, a Bergius_pier converter, aPier converter or a combination of a Pier converter with a MtLconverter.
 60. The apparatus according to claim 27 further comprising acontrol unit for open-loop controlling or close-loop regulating thepressure of the synthesis gas in the CO converter.